Computations of open channel flows in a shallow sharp bend using depth-averaged 2D models with secondary flow effects

抄録

Secondary flow effects are considered in two dimensional depth averaged model to simulate the open channel flow in a sharp bend channel, and the simulated flow structures are compared with different kind of secondary flow models: Nays2DH solver without considering the secondary flow effect in flow equations; Onda et al model using nonlinear secondary flow equation with additional nonlinear transport equation for secondary flow strength; a new nonlinear secondary flow model which considers the secondary flow effect on the vertical distribution of streamline velocity and the inertia effect of the secondary flow advection. These three model results are compared to experimental results. Large difference of flow structures between Nays2DH and the experimental result means that 2D (two-dimensional) depth averaged model without secondary flow effect is inapplicable for sharp bend flow prediction. Obvious weaker deviation of the mainstream from inner bank of Onda et al model than that of the experiment shows that Onda et al model is insufficient for strong nonlinear phenomenon in a sharp bend. Mainstream deviation and other unreasonable structures in linear model from the experiment are similar proofs that a refined nonlinear secondary flow modelling is necessary in simulation of sharp bend flow.